Post mold cooling apparatus and method having transverse movement

ABSTRACT

Post mold cooling apparatus and method having transverse movement preferably includes structure and/or steps for cooling a plurality of plastic articles molded on a row of mold cores. A post mold cooling device is provided having (i) a first row of cooling tubes configured to hold a first plurality of the molded plastic articles, and (ii) a second row of cooling tubes configured to hold a second plurality of the molded plastic articles. A cooling station is disposed adjacent the cooling device and is configured to provide a cooling fluid to an interior of both the first and second pluralities of molded articles inside the respective first and second rows of cooling tubes. Movement structure is configured to (i) provide a rotational movement to cause the first and second pluralities of molded articles inside the respective first and second rows of cooling tubes to be presented to the cooling station, and (ii) provide a transverse, axial movement to alternately cause the first row of cooling tubes and then the second row of cooling tubes to be presented to the row of mold cores.

This is a Continuation-In-Part of U.S. patent application Ser. No.10/147,360, filed May 17, 2002, now U.S. Pat. No. 6,817,855, which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for coolingmolded plastic articles after molding is finished. In particular, thepresent invention relates to method and apparatus for a post moldcooling (“PMC”) device having at least two opposed faces. The method andapparatus are particularly well suited for cooling injection moldedthermoplastic polyester polymer materials such as polyethyleneterephthalate (“PET”) preforms.

2. Related Art

A variety of post mold cooling methods are currently employed oninjection molding machines (e.g., an Index machine platform) in varioussequences to optimize the cooling of freshly molded plastic parts. Someparts (for example plastic preforms) are typically injection-moldedusing PET resin, and can have wall thicknesses varying from about 2.00mm to greater than 4.00 mm, and consequently require extended coolingperiods to solidify into substantially defect-free parts. Heavy walledparts (such as those made from a material that has a high resistance tothermal heat transfer, like plastic resin) can exhibit “reheating”phenomena that can produce defective parts after they have been ejectedfrom the mold.

In the case of PET preforms some of these manufacturing defects are:

-   -   Crystallinity: The resin recrystallizes due to the elevated        temperature of the core resin not cooling quickly enough. The        white appearance of the crystals impairs the clarity of the        final product and provides an area of potentially weakness in a        resultant blown product.    -   Surface blemishes: The ejected performs, initially having        solidified surfaces are reheated by the core material which        causes the surface to soften and be easily marred. Sometimes        this surface reheating can be severe enough to cause touching        parts to weld together.    -   Geometric inaccuracies: Handling partly-cooled performs or        attempting to further cool them in devices that do not maintain        their geometric shape while their surfaces are reheated can        cause the preform's round diameter to become oval shaped or the        smooth surface to become wrinkled or non-linear.

The above-noted problems could be alleviated somewhat by extending thecooling time of the injection molded performs in their mold. However,this will cause the injection molding cycle to be lengthy, typically 25seconds or longer, wherein the majority of this time was used solely forcooling purposes. In an effort to improve the production efficiency ofthis process, several techniques are employed to perform a post moldcooling function, wherein partially cooled preforms are ejected from theinjection mold after an initially cooled surface skin has formed toallow the part to be ejected without deformation. The partially cooledpreforms are then handed off to a downstream device that continues tohold the preform while removing the remaining heat so that the preformcan subsequently be handled without damage. Typically, the preformsurface temperature needs to be lowered to about 70° C. to ensure safehandling.

The early ejection of partially cooled preforms released the injectionmolding equipment earlier in the molding cycle, thereby significantlyimproving the production efficiency of the equipment. Injection moldingcycle times typically were halved from 25 seconds to about 12 seconds orless in some instances depending on the preform design being molded.

Some examples of post mold cooling technology are shown in U.S. Pat.Nos.: 4,729,732; Re. 33,237; 5,447,426; and 6,171,541.

Another approach to extending the cooling time for preforms is toutilize a turret molding machine in which more than one set of injectionmolding cores are employed. An example is the Index machine, shown inU.S. Pat. Nos.: 5,728,409; 5,830,404; 5,750,162; and 5,817,345, whichdisclose using a turret block having four faces and four core sets thatare sequentially mated with one cavity set to hold the injection moldpreforms. Preforms molded on this kind of equipment can be produced inmolding cycle times of typically 10-13 seconds.

In Index machines with fewer core side tooling sets employed, additionalpost mold cooling devices are used to complete the preform cooling andmaintain cycle time benefits. Examples of Index machines with post moldcooling devices are shown in U.S. Pat. Nos.: 6,059,557; 6,123,538;6,143,225; and 6,113,834.

One technique for improving the rate of heat transfer from a coolingpreform is to pressurize its interior volume while cooling it in acavity. This method helps keep the preform's exterior surface in contactwith the cooling cavity surface, and counters the shrinkage of thepreform that tends to separate the two surfaces. This allows good heattransfer to be maintained. Examples of pressurized preform cooling areshown in U.S. Pat. Nos.: 4,950,152; and 5,679,306, and in EP 0 900 135.

U.S. Pat. No. 6,113,834 to Kozai discloses a post mold cooling device(PMC) that unloads preforms from an Index preform molding machine intocooling tubes. FIGS. 8-14 disclose mounting multiple sets of tubes on asingle plate so that multiple molding sets of preforms can be cooled bythe tubes during several injection molding cycles, thereby extending thecooling time of each preform during its stay in the PMC device. Thispatent also discloses blowing a cooling fluid from the PMC device ontothe exposed gate area of the freshly molded preforms while they arestill on the injection molding cores prior to their transfer to the PMCdevice. However, this post mold cooling technique is somewhat limited bythe absence of a more efficient means to cool the interior of thepreform. Also, there is no means for efficiently translating the turretto access the various sets of cooling tubes.

Therefore, there is a need for a post-mold cooling method and apparatus,which provides rapid, efficient cooling while further reducing themolding cycle time to further decrease the cost of producing moldedplastic pieces.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, structure and/orsteps are provided for cooling a plurality of plastic articles molded ona plurality of mold portions. A cooling device is provided having (i) afirst plurality of cooling structures configured to hold a firstplurality of molded plastic articles, and (ii) a second plurality ofcooling structures configured to hold a second plurality of moldedplastic articles. A cooling station is disposed adjacent the coolingdevice and configured to provide a cooling fluid to an interior of thefirst and second pluralities of molded articles inside the respectivefirst and second pluralities of cooling structures. A movement structureis provided and is configured to (i) provide a first movement to causerelative movement of the cooling device and the mold portions to causethe first and second pluralities of molded articles inside therespective first and second pluralities of cooling structures to bepresented to the cooling station, and (ii) provide a second movement,different from the first movement, to alternately cause the firstplurality of cooling structures and then the second plurality of coolingstructures to be presented to the plurality of mold portions. Each facepreferably mounts cooling tubes in multiple sets. The preferredembodiment also has a top mounted CoolJet/Supercool device, and a meansfor axially moving the cooling block transversely to provide loading ofthe different cooling tubes sets from an Index preform molding machine.

According to a second aspect of the present invention, structure and/orsteps are provided for an injection molding machine, including a moldcavity half having a plurality of mold cavities. A mold core half isprovided having a plurality of mold cores corresponding to the pluralityof mold cavities. A mold movement structure causes relative movementbetween the mold cavity half and the mold core half to cause a pluralityof molded articles to be extracted from the plurality of mold cavitiesduring each of a plurality of mold cycles. A cooling device is movablewith respect to the mold core half and has a plurality of cooling tubesto hold the plurality of molded articles extracted from the plurality ofmold cavities. A cooling device movement structure is coupled to thecooling device and is configured to maintain the plurality of moldedarticles in the plurality of cooling tubes for a time period exceedingtwo of the mold cycles.

According to a third aspect of the present invention, structure and/orsteps are provided for moving a cooling turret with respect to a plasticinjection molding machine portion. Linear movement structure isconfigured to cause the cooling turret and the plastic injection moldingmachine portion to move relatively toward and away from each other.Rotary movement structure is configured to cause relative rotationalmovement between the cooling turret and the plastic injection moldingmachine portion. Axial movement structure is configured to causerelative axial movement between the cooling turret and the plasticinjection molding machine portion.

According to a fourth aspect of the present invention, structure and/orsteps are provided for a cooling apparatus for a plastic injectionmolding machine having a plurality of mold cores disposed in at leastone row. A post mold cooling device is provided and is moveable withrespect to the plurality of mold cores. A rotatable cooling turret iscoupled to the post mold cooling device and has two faces, each facehaving at least first and second rows of cooling tubes. A coolingstation is coupled to the post mold cooling device and has a pluralityof cooling probes configured to project a cooling fluid to an interiorof molded articles inside both the first and second rows of coolingtubes of one of the faces of the cooling turret. A first movementstructure is configured to cause the post mold cooling device to movetoward and away from the plurality of mold cores. A second movementstructure is configured to cause the cooling station to move toward andaway from the cooling turret. A third movement structure is configuredto cause the cooling turret to rotate to alternately present the firstand second cooling turret faces to the cooling station. A fourthmovement structure is configured to cause the cooling turret to moveaxially with respect to its axis of rotation to alternately present thefirst row of cooling tubes and then the second rows of cooling tubes ofa cooling turret face to the row of mold cores.

According to a fifth aspect of the present invention, structure and/orsteps are provided for cooling a row of molded articles disposed on arow of mold cores. The row of molded articles is transferred to a firstrow of cooling tubes disposed on a cooling device. The row of moldedarticles in the first row of cooling tubes is moved to a coolingstation. At the cooling station, a cooling fluid is injected into theinterior of each molded article in the row of molded articles. The rowof molded articles is moved to a position away from the cooling station.The row of molded articles is then moved back to the cooling station. Atthe cooling station, once again, a cooling fluid is injected into theinterior of each molded article in the row of molded articles. Finally,the row of molded articles is moved to an ejection station.

Thus, the present invention advantageously provides post-mold coolingmethod and apparatus for efficiently cooling molded plastic pieces.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will now be describedwith reference to the accompanying drawings in which:

FIG. 1 is a schematic side view of the clamp half of an Index preformmolding machine including a PMC device according to a preferredembodiment of the present invention.

FIG. 2 is a schematic front view of the PMC device of FIG. 1 prior tounloading and insertion of a CoolJet™/Supercool device.

FIG. 3 is a schematic front view of the PMC device of FIG. 1 unloadingselected parts and with the CoolJet™/Supercool device in conditioningposition.

FIG. 4 is a schematic front view of the PMC device of FIG. 1 immediatelyprior to loading freshly molded preforms into the vacated cooling tubes,showing the transverse motion during rotation of the block.

FIG. 5 is a schematic front view of the PMC device of FIG. 4 immediatelyafter loading preforms into the vacated tubes, and shows opposedtransverse motion during rotation of the block.

FIG. 6 is a schematic front view of the PMC device prior to unloadingand insertion of the CoolJet™/Supercool device.

FIG. 7 is a schematic front view of the PMC device unloading selectedparts and with the CoolJet™/Supercool device in conditioning position.

FIG. 8 is a schematic front view of the PMC device immediately prior toloading freshly molded preforms into the vacated cooling tubes.

FIG. 9 is a schematic side view of the PMC device prior to unloading andinsertion of the CoolJet™/Supercool device.

FIG. 10 is a schematic side view of the PMC device immediately afterloading preforms into the vacated tubes.

FIG. 11 is a sequence chart showing a complete molding and PMC coolingsequence for one set of preforms.

FIGS. 12 a-12 y comprise a series of schematic representations of theposition of the PMC block for its complete cycle.

FIG. 13 is a schematic side view of an alternate embodiment of the PMCdevice showing three faces.

FIG. 14 is a schematic side view of a further alternate embodiment ofthe PMC device without a cooling station or blower.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS 1.Introduction

The present invention will now be described with respect to severalembodiments in which an Index plastic injection molding machine uses a(preferably rotating) take out turret to extract plastic preforms from amolding unit, and sequentially to move these preforms to a coolingstation. Preferably, the cooling station comprises a so-called CoolJet™device in which a cooling pin is inserted into each preform, cooling airis injected to the interior tip of the preform, and the cooling airflows down the inside surface of the preform to the outside. The coolingstation may also comprise a so-called SuperCool device in which acooling pin is inserted into each preform, each preform ispressure-sealed, and cooling air is injected into the interior of thepreform. The pressure causes the outside walls of the preform to contactthe inside walls of the take out cavity, thus effecting cooling on boththe inside and outside surfaces of the preform. The cooling station mayalso comprise a combination of CoolJet™ and SuperCool devices and/orequivalent structures. Nevertheless, it should be understood that theteachings and claims of the subject invention are equally applicable toother molding processes used for producing other relatively thick-walledhollow articles. For example, the present invention will findapplicability in many molding technologies beyond injected-moldedplastic preforms, such as the molding of containers, pails, trays, paintcans, tote boxes, and similar products, or other molded productspossibly with non-circular cross-sectional shapes, etc.

2. The Structure

FIG. 1 shows the clamp half of an Index preform molding machine 1comprising the stationary platen 10 and a rotating turret block assembly11. The turret block assembly 11 is mounted on journals and is typicallycarried by two carriers 12 which are releasably connected to thestationary platen 10 by tiebars 13. The ends of the tiebars arereleasably connected to clamping piston assemblies 14 mounted to thestationary platen 10. The carriers 12 are guided and slide on linearbearings 15 attached to the machine base 16. The carriers 12 and themolding turret block assembly 11 are moved toward and away from thestationary platen 10 by well-known drive means (not shown). Preform moldhalf 91 (comprising a hot runner and mold cavities) is mounted to thestationary platen 10 and sequentially engages one or more mold coldhalves 17 a and 17 b that are mounted to the opposed faces of themolding turret block assembly 11. When the mold halves are separated bymoving the carriers away from the stationary platen, the molding turretblock assembly 11 and the attached mold cold halves 17 can be rotated,for example, by a servo motor 18 via a drive belt 19 and a pulley 20. Aninjection unit 21 supplies melted resin for injection into the mold.

A post mold cooling (PMC) device or assembly 30 includes a second pairof carriers 31 a and 31 b that also are guided and slide on linearbearings 15 attached to the machine base 16. A cooling turret block 32is mounted between the carriers 31 a and 31 b, and is rotatabletherebetween. The PMC device 30 is movable along the machine basetypically through use of a motor drive 90 and a belt 33 such that theassembly can move toward or away from the molding turret block assembly11.

FIG. 2 shows a front view of the PMC device in its unloadingorientation. The cooling turret block 32 is carried on linear bearings34 a and 34 b and 35 such that it can move transversely along its axisof rotation or substantially parallel to its axis of rotation betweenthe carriers 31 a and 31 b. This motion may be caused by a cylinder 36that is mounted on the cooling turret block 32. A cylinder rod 37 isattached to a bearing arm 38 that also carries part of the linearbearing assemblies 34 a and 34 b. The bearing arm 38 is journaled in thecarrier 31 a, and is attached via a gearbox 39 to a servo drive motor 40that causes the arm 38 and the cooling turret block assembly 32 torotate. The opposed end of the cooling turret block 32 is supported by arotary services union 41 that is itself supported on a bearing assembly35 such that the transverse motion of the cooling turret block 32 isguided along the bearing 35 to an outboard position shown in FIG. 4. Theamount of this motion is determined by the pitch between the multiplerows of cooling tubes mounted on the PMC mounting plates, to bedescribed below.

The rotary services union 41 provides a rotary connection for pneumatic,hydraulic, cooling fluid, and electrical services from the machine baseto both the cooling turret block 32 and the CoolJet™/Supercool assembly42 (to be described below) mounted on top of the carriers 31 a and 31 b.These services are conveyed via flexible conduits 43 from the base 16 tothe union 41 so that the supply can be maintained regardless of theposition of the PMC on the machine base 16.

FIG. 2 also shows the preform cooling tubes 44 mounted on a plate 45.There are sufficient tubes 44 for multiple sets of preforms 2 beingmolded by the injection unit. In the illustration there are 32 tubesmounted on plate 45, these being sufficient for two molding setsproduced by an exemplary 16 cavity injection mold. Of course, a set maycomprise any number of tubes greater than or equal to two. Further,there may be two, three, or more sets of tubes coupled to the plate 45.A plate 45 is mounted on one side, face A, of the cooling turret block32. A second plate 48 and corresponding tubes 49 (32 in number) aremounted on the opposed face B of the cooling block 32. The tubes arearranged in two alternate sets on each face (e.g., see FIG. 4), each setmatching the pitch of the injection mold cores. The first set aligningwith the mold is called row 1 and the second set offset from row 1 by anamount X is called row 2. If sufficient space allows, additional setsmay be provided on each face.

In the present embodiment the total number of tubes on both sides of thecooling turret block 32 can hold four sets of parts molded by theinjection unit, thus parts can be treated for four cycles after ejectionfrom the molding turret 11. Clearly if there is space for additionaltubes, an extended treatment time can be provided. Further, depending onthe design, the parts may be treated for two, three, four, or moremolding cycles. Further, cooling turret block 32 could have more thantwo faces for mounting sets of tubes.

FIG. 13 shows an alternate embodiment mounting three such plates, othersmounting four or more are also possible. Further, there are situationswhere the parts being molded are thin enough not to require internalcooling by means of an inserted cooling tube or external cooling bymeans of a blower. In this situation the machine would be configured asshown in FIG. 14 in which the cooling station atop the carriers 31 a and31 b and the blower have been removed.

FIG. 2 also shows the CoolJet/Supercool unit 42 mounted above thecooling turret block 32. The unit is moved vertically by cylinders 50.The unit may comprise only CoolJet™ blowing pins, only SuperCool™ pinsfor expansion and cooling of the preforms, or a combination of bothtypes in, for example, alternate sets to provide a variety of treatmentoptions to the preforms 2 presented to the unit. The unit includesmultiple cooling pins 51, in a number sufficient to match thecorresponding number of cooling tubes 44 on one face of the coolingturret block 32. In the preferred embodiment, there are 32 cooling pinsmounted in a matrix matching the corresponding tubes 44. The coolingpins 51 are mounted on a distributor plate 52 that provides pressurizedand/or nonpressurized coolant flow to each cooling pin. Alternatively,this plate 52 may simply be a plenum, pressurized by a blower mounted onthe unit 42 (not shown). If pressurized cooling fluid (liquid and/orgas) is supplied to the distributor plate 52, it is conveyed by aflexible conduit 53 that connects the plate 52 to the services union 41or an alternate point on the PMC device 30.

FIG. 1 also shows a blower 60 mounted on the PMC device 30 that candirect a flow of air toward the molded parts while they are still ontheir cores 70 a on the molding turret 11, as indicated by arrows F.This allows supplementary cooling of the parts (especially their gateareas) while they are waiting to be transferred to the PMC device 30.For clarity, the blower 60 is omitted from the views of the PMC device30 in other figures. An alternate embodiment (not shown) mounts one ormore blowers on the cooling turret block 32 or on the carriers 31 a and31 b such that they are closer to the parts on the cores onto which theyare directing their air flow and from such a location that optimizes theflow distribution evenly over the matrix of injection cores on the indexblock when in the transfer position, as shown in FIG. 1. A furtheralternate embodiment (not shown) mounts the blowers on the machine baseand ducts, mounted on the carriers 31 a and 31 b, align with the blowerswhen the PMC device is in the transfer position, so to direct the flowdistribution evenly over the matrix of injection cores on the indexblock when in the transfer position, as shown in FIG. 1. While theturrets 11 and 32 are configured for rotary movement, alternativeembodiments include molding and/or cooling plates which may be movedlinearly or curvelinearly with respect to the mold and themolding/cooling structures, as may be required.

3. The Process

In operation, the Index molding turret block 11 and the mold cold half17 a are moved to form a closed mold with a hot mold half 91. A clampforce is applied to the mold via, in the preferred embodiment, clamppistons 14 acting through tiebars 13. The mold is filled by theinjection unit 21, and after a hold and cooling time, the mold is openedby moving the molding turret 11 and the cold half 17 a away from thestationary platen 10 a sufficient distance to clear the rotational arcof the cores 70 a on the molding turret 11. In a two faced turret systemthe turret block is rotated through 180 degrees to align the first setof mold cores 70 a carrying the freshly molded parts thereon with thePMC device cooling tubes 44. The second set of mold cores 70 b are nowaligned with the cavity half 91 the mold is closed, and the cyclerepeated to make a second set of parts on the second set of cores 70 b.A typical injection molding cycle time is about 10 seconds.

Meanwhile, the blower 60 directs a cooling flow of air onto the parts onthe cores 70 a. Just before the molding cycle taking place on cores 70 bis completed, the PMC device 30 is moved toward the molding turret 11,and the molded parts on cores 70 a are transferred from the injectionmolding turret 11 to row 1 of the cooling tubes 44 mounted on face A ofthe cooling turret block 32 of the PMC device 30. The PMC device 30 isthen moved away from the molding turret 11 a sufficient distance toclear the rotational arc of the cooling tubes 44 when loaded withpreforms.

The cooling turret block 32 is then rotated through 90 degrees to alignthe tubes and their parts vertically with the CoolJet™/Supercool unit42, as shown in FIG. 2. This unit is then moved via cylinders 50downwards to insert cooling pins 51 into all the preforms in all thetubes 44, and cooling fluid is ejected from the tubes to cool theinterior of the parts. The interior of the parts may be pressurizedand/or the cooling fluid may be directed to a distal tip of the interiorof the part. Meanwhile, as shown in FIG. 3, some of the parts 2 in thetubes 49 mounted on the opposed face B of the cooling turret block 32are ejected beneath the cooling block onto a conveyor (not shown). Theejected parts have thus been traveling in the PMC device 30 for four ormore molding cycles depending on the number of cooling tube setsinstalled on the PMC and the number of faces utilized to support coolingtubes. For a 10 second injection molding cycle time the parts will havebeen treated in the PMC unit for approximately 40 seconds.

In the preferred embodiment, photo eye sensors (not shown) mounted onthe inboard surfaces of the carriers 31 a and 31 b and aligned withreflectors (not shown) mounted on the cooling turret block 32 faces Aand B check to ensure the appropriate parts 2 have been completelyejected from the cooling tubes and that any auxiliary ejector bars (notshown) have correctly retracted prior to rotation of the turret block 32thereby ensuring the risk of equipment collision is avoided. Analternate part removal embodiment is by use of a conventional robotdevice (not shown) mounted on the machine base 16 or the adjacent floorhaving a take-off plate positioned such that parts can be transferred toit when the cooling turret block 32 is in the transfer position shown inFIG. 1 thereby vacating the cooling tubes slightly earlier in the PMCdevice cooling cycle.

The CoolJetT™/Supercool unit 42 is retracted from its inserted position,shown in FIG. 3, by the cylinders 50 a sufficient vertical distance toclear the rotational arc of the cooling tubes 44 and their loadedpreforms. The cooling turret block 32 is then rotated 90 degrees toalign the vacated tubes with the next set of freshly molded parts on themold cores 70 b. The parts are transferred and the sequence continues.When the next vacated set of tubes occurs that is not aligned with theinjection cores, the cooling turret block 32 is moved axially by thecylinder 36 (as the turret rotates) to align the vacated tubes with thenext freshly molded parts on the cores 70 a. That is, the cooling turretblock 32 is moved axially along an axis parallel to that of its rotationto present the next set of cooling tubes to the parts 2 on the turretcores 70 a or 70 b.

FIG. 4 shows an arrow X indicating the axial translation of the coolingturret block 32, to align the vacant tubes during the rotary motion ofthe cooling block, which is indicated by a rotational arrow R₁.

FIG. 5 shows the freshly molded parts 2 loaded into the cooling tubes44. An arrow Y shows the reverse axial translation of the cooling turretblock 32 during the continuing rotation of the cooling block, which isindicated by a rotational arrow R₂.

FIG. 6 shows the continuing sequence with the cooling tubes 44 alignedfor treatment by the CoolJet™/Supercool unit 42. Note that at eachinsertion of the pins 51, all the cooling tubes are loaded with preformsfor cooling. Thus, in the entire PMC cycle, each of the preformspreferably has two or more treatments from the CoolJet™/Supercool unit42. This ensures that any latent migration of residual heat within thewall sections of even the thickest parts of the preform is treatedrepeatedly, thereby minimizing the opportunity for recrystallization ofthe resin to occur. Note that a three-sided cooling turret block 32would result in molded parts being cooled for six molding cycles, and atwo-sided cooling turret block would result in molded parts being cooledfor four molding cycles. Thus, varying the number of faces on thecooling block will vary the number of injection molding cycles in whichthe molded parts can be cooled.

FIG. 7 shows the ejection of the parts 2 from alternate rows of face Awhile application of CoolJet™/Supercool treatment is occurring at faceB. The sequence continues as shown in FIG. 8 until the parts firstloaded into tubes in row 1 face A have been ejected whereupon thesequence recycles. In the case of the preferred embodiment, for eachcomplete cycle of the PMC device 30, four cycles of the injection unittake place. If additional cooling tubes are provided in the PMC device30, additional molding cycles of the injection unit may be possible.Note that the ejection of the molded parts 2 may be accomplished bymechanical means or pneumatic means, as are well-known in the art.

FIG. 9 shows a side view of the PMC device 30 just prior to insertion ofthe CoolJet™/Supercool cooling pins 51. In FIG. 10, the PMC device 30has rotated to accept the just-molded preforms 2 into the vacatedcooling tubes 49.

For clarification, FIG. 11 is a sequence chart showing the operationsoccurring at each stage of the injection molding and cooling cycles.FIGS. 12 a-12 y schematically depict the structure during various phasesof the sequence chart. The sequence chart and schematics will bedescribed with respect to injection molding cycles, cooling turretcycles, and those activities that take place in the molding turret 11and the cooling turret block 32. The control of the various molding andmovement operations may be performed with one or more general purposecomputers, PCs, processors, application specific integrated circuits,digital signal processors, hard-wired circuits, motors, servomotors,stepper motors, pressure sensors, temperature sensors, etc.

Injection molding cycle 1 begins when the mold halves close, the clampis activated, and molten plastic is injected into the mold and heldtherein for a predetermined period of time. The just-molded articles areallowed to cool in the mold for another predetermined period of time,and the mold halves are opened. The molding turret 11 is then moved awayfrom the mold cavity half and rotated 180 degrees where the cooling fan60 blows cooling air on the just-molded parts. The molding turret 11immediately moves back toward the mold cavity half, and injectionmolding cycle 2 begins, in the meantime the previously molded partsremain on the cores until just before the mold is due to open again. ThePMC device 30 is moved toward the molding turret 11 and the parts aretransferred to the cooling turret block 32 immediately prior to the moldbeing opened again.

In the cooling turret block 32, the previously-molded parts 2 a ₁ (seeFIG. 12 a) are loaded into the cooling tubes 44 of row 1 of face A. Thecooling turret block 32 is then moved away from the molding turret 11and rotated 90 degrees toward the CoolJet™/Supercool unit 42 (see FIG.12 b). The CoolJet™/Supercool unit 42 is then moved downward, thecooling pins 51 are inserted into the preforms 2 a ₁ (see FIG. 12 c),and the preforms are pressurized and/or cooled (see FIG. 12 d). Notethat the cooling pins 51 also cool preforms 2 a _(2-prior), which arepreforms from a prior molding cycle located in row 2 of face A (to bedescribed in greater detail below). The preforms 2 a ₁ are thenvented/blown to complete the cooling engagement, and the cooling unit 42is moved upward to disengage the cooling pins 51 from the preforms 2 a₁. At the same time, appropriate mechanical and/or pneumatic means areactivated to eject the previously-cooled preforms 2 b _(1-prior) (from aprior injection molding cycle) from the bottom of cooling turret block32 (see FIG. 12 e). This step occurs approximately midway throughinjection molding cycle 3.

After the molded preforms 2 b have been ejected from the cooling turretblock 32, it is rotated 90 degrees (see FIG. 12 f) to present thecooling tubes 49 to the molding turret 11. The PMC device 30 is thenmoved toward molding turret 11, and previously molded preforms 2 b ₁ aretransferred to the cooling tubes 49 of row 1 of face B (see FIG. 12 g).Then, the steps described above with respect to preforms 2 a ₁ (seeFIGS. 12 a-12 f) are repeated for preforms 2 b ₁ (see FIGS. 12 g-121).During these steps, the preforms 2 a ₁ on face A of cooling turret block32 continue to cool. Note that in FIG. 12 k, it is not theabove-described preform 2 a ₁ which is ejected, but the preform 2 a_(2-prior) from a prior injection molding cycle which is ejected fromrow 2 of face A. This unloading step also occurs approximately midwaythrough injection molding cycle 4. Notably, after the cooling turretblock 32 is rotated 90 degrees in FIG. 121, the cooling turret block 32is moved axially to present the cooling tubes 44 of row 2 of face A tothe molding turret 11.

After rotating and axially translating the cooling turret block 32, thePMC device 30 is moved toward the molding turret 11, and preforms 2 a ₂are transferred to the cooling tubes 44 of row 2 of face A of thecooling turret block (see FIG. 12 m). Thereafter, the same steps asdescribed above with respect to preforms 2 a ₁ (FIGS. 12 a-12 f) arerepeated for preforms 2 a ₂ (see FIGS. 12 m-12 r). Note in FIG. 12 pthat the cooling pins 51 cool both the preforms 2 a ₂ in row 2 of faceA, as well as preforms 2 a ₁ in row 1 of face A. Thus, the preforms 2 a₁ are cooled twice by the cooling unit 42. Note also that in FIG. 12 q,the preforms 2 b _(2-prior) are ejected while the preforms 2 b ₁ remainin the cooling turret block 32. This step also occurs approximatelymidway through injection molding cycle 5.

When the cooling turret block 32 has been rotated so that face B isagain presented to molding turret 11, the PMC device is moved toward themolding turret 11, and preforms 2 b 2 are transferred to the coolingtubes 49 of row 2 of the cooling turret (see FIG. 12 s). Note thatpreforms 2 a 1, 2 a 2, and 2 b 1 remain in the cooling turret block foradditional cooling. Thereafter, the same steps as described above withrespect to preforms 2 b 1 (FIGS. 12 g-12 l) are repeated for preforms 2b 2 (see FIGS. 12 s-12 x). In FIG. 12 w, preforms 2 a 1 are finallyejected from the cooling turret block 32, during injection molding cycle6, more than four cycles after their molding, and after rotating one andthree-quarters times (630 degrees) around the cooling turret block 32.This extension of the cooling time allows the preforms 2 a 1 to properlysolidify without the crystallization problems discussed earlier. In FIG.12 x, the cooling turret block 32 is rotated 90 degrees as well as beingmoved axially to present the cooling tubes 44 of row 1 of face A to themolding turret 11.

In FIG. 12 y, the cooling turret block 32 is in the same position asthat depicted in FIG. 12 a, and the next set of preforms 2 a _(1-next)are loaded into the cooling tubes 44 of row 1 of face A, and theabove-described steps are repeated.

The above-described steps thus provide an optimized embodiment in whicha minimum amount of injection and PMC tooling components are required inorder to produce substantially defect-free high quality preform parts ata fast production cycle. Only one cooling station is used and yet twotreatment opportunities are provided to each preform. Note, however,that additional cooling stations could be provided at any one or more ofthe three other positions to which the faces of the cooling turret blockare rotated during the above-described process.

4. Advantageous Features

Advantageous features according to the preferred embodiments include:

-   -   A PMC cooling turret block with translational motion preferably        along an axis parallel to its axis of rotation.    -   A PMC unit that provides two or more separate and possibly        different treatment events for each part.    -   A PMC unit that carries a blower unit for projecting a stream of        cooling air onto the parts positioned on their cores prior to        transfer.

5. Conclusion

Thus, what has been described is a method and apparatus for efficientlycooling molded plastic articles, achieving reduced cycle time and cost.

While the present invention shortens the manufacturing time of blowmolded container preforms generally having circular cross-sectionalshapes perpendicular to the preform axis, those skilled in the art willrealize the invention is equally applicable to other molded productspossibly with non-circular cross-sectional shapes, such as, pails, paintcans, tote boxes, and other similar products requiring a similar generalconfiguration and mold design characteristics as with the preforminjection mold.

The individual components shown in outline or designated by blocks inthe attached Drawings are all well-known in the injection molding arts,and their specific construction and operation are not critical to theoperation or best mode for carrying out the invention.

While the present invention has been described with respect to what ispresently considered to be the preferred embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments. To the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

All U.S. and foreign patent documents discussed above are herebyincorporated by reference into the Detailed Description of the PreferredEmbodiment.

1. Apparatus configured to cool a plurality of plastic articles formedin respective molds during at least two consecutive molding cycles, theplurality of plastic articles loadable into the apparatus from a fixedregistration position for each mold, the apparatus comprising: a) arotatable cooling turret block having an axis of rotation and at least:i) a first plurality of cooling structures configured to hold a firstplurality of molded plastic articles formed in a first molding cycle;and ii) a second plurality of cooling structures configured to hold asecond plurality of molded plastic articles formed in a differentmolding cycle than the first molding cycle; b) a drive assembly coupledto the rotatable cooling turret block to cause the rotatable coolingturret block to rotate about the axis of rotation, the drive assemblyfurther configured to cause linear displacement of the rotatable coolingturret block in a direction substantially parallel to the axis ofrotation, whereby the linear displacement causes the first plurality ofcooling structures and then the second plurality of cooling structuresto be presentable to and aligned with the fixed registration positionfor receipt of molded articles thereinto.
 2. Apparatus according toclaim 1, further comprising a complementary cooling station locatedadjacent said rotatable cooling turret block, wherein the driveassembly, upon causing rotation of the rotatable cooling turret block,causes the first and second pluralities of cooling structures to bepresented together to the complementary cooling station.
 3. Apparatusaccording to claim 2, wherein the complementary cooling station isconfigured to deliver a flow of cooling fluid into an interior of moldedarticles held within the first and second pluralities of coolingstructures.
 4. Apparatus configured to cool a plurality of plasticarticles disposed in/on a plurality of mold portions, comprising: acooling device having (i) a first plurality of cooling structuresconfigured to hold a first plurality of molded plastic articles, and(ii) a second plurality of cooling structures configured to hold asecond plurality of molded plastic articles, said first plurality ofcooling structures being disposed in rows interleaved with correspondingrows of said second plurality of cooling structures; a cooling stationdisposed adjacent said cooling device and configured to provide acooling fluid to an interior of the first and second pluralities ofmolded articles inside the respective first and second pluralities ofcooling structures; and movement structure configured to (i) provide afirst movement to cause relative movement between said cooling deviceand the mold portions to cause the first and second pluralities ofmolded articles inside the respective first and second pluralities ofcooling structures to be presented to said cooling station, and (ii)provide a second movement, different from the first movement, toalternately cause the first plurality of cooling structures and then thesecond plurality of cooling structures to be presented to the pluralityof mold portions.
 5. Apparatus according to claim 4, wherein saidmovement structure provides the first movement as a rotary movement andthe second movement as a linear movement parallel to an axis of therotary movement.
 6. Apparatus according to claim 4, wherein saidmovement structure causes the first plurality of molded articles to berotated more than 360 degrees with respect to the plurality of moldportions.
 7. Apparatus according to claim 4, wherein said movementstructure causes the first plurality of molded articles to be held insaid cooling device for at least four cycles of a molding operation ofthe plurality of mold portions.
 8. Apparatus according to claim 4,wherein said movement structure causes one cooling cycle of said coolingdevice to be substantially equal to four molding cycles of the pluralityof mold portions.
 9. Apparatus according to claim 4, wherein saidcooling station is configured to provide a cooling fluid to a distal tipof the interior of the first and second pluralities of molded articlesinside the respective first and second pluralities of coolingstructures.
 10. Apparatus according to claim 4, wherein said coolingstation is configured to provide a pressurized cooling fluid to theinterior of the first and second pluralities of molded articles insidethe respective first and second pluralities of cooling structures. 11.Apparatus according to claim 4, further comprising blower structurecoupled to said cooling device and configured to provide cooling air toexteriors of the plurality of plastic articles disposed in/on aplurality of mold portions.
 12. Apparatus according to claim 4, whereinsaid first plurality of cooling structures comprises a first pluralityof rows of cooling tubes, and wherein said second plurality of coolingstructures comprises a second plurality of rows of cooling tubes whichare interleaved with the first plurality of rows of cooling tubes. 13.Apparatus for moving a cooling turret with respect to a plasticinjection molding machine portion, comprising: linear movement structureconfigured to cause the cooling turret and the plastic injection moldingmachine portion to move relatively toward and away from each other;rotary movement structure configured to cause relative rotationalmovement between the cooling turret and the plastic injection moldingmachine portion; and axial movement structure configured to causerelative axial movement between the cooling turret and the plasticinjection molding machine portion in a direction parallel to the axis ofrelative rotational movement between the cooling turret and the plasticinjection molding machine portion.
 14. Apparatus according to claim 13,further comprising the cooling turret, wherein the cooling turret hasfirst and second interleaved rows of cooling tubes disposed on each oftwo cooling turret faces, and wherein said axial movement structuremoves the cooling turret to alternately present the first and secondinterleaved rows of cooling tubes disposed on each of the two coolingturret faces to a row of mold cores on the molding machine portion. 15.Apparatus according to claim 14, further comprising a cooling stationhaving a plurality of cooling structures which respectively correspondto both the first and second rows of cooling tubes, and wherein saidrotary movement structure rotates the cooling turret to present thefirst and second rows of cooling tubes to the plurality of coolingstructures.
 16. Cooling apparatus for a plastic injection moldingmachine having a plurality of mold cores disposed in at least one row,comprising: a post mold cooling device moveable with respect to theplurality of mold cores; a rotatable cooling turret coupled to said postmold cooling device and having two faces, each face having at leastfirst and second rows of cooling tubes; a cooling station coupled tosaid post mold cooling device and having a plurality of cooling probesconfigured to project a cooling fluid to an interior of molded articlesinside both the first and second rows of cooling tubes of one of thefaces of said cooling turret; first movement structure configured tocause said post mold cooling device to move toward and away from theplurality of mold cores; second movement structure configured to causesaid cooling station to move toward and away from said cooling turret;third movement structure configured to cause said cooling turret torotate to alternately present the first and second cooling turret facesto said cooling station; and fourth movement structure configured tocause said cooling turret to move parallel with respect to its axis ofrotation to alternately present the first row of cooling tubes and thenthe second rows of cooling tubes of a cooling turret face to the row ofmold cores.
 17. Apparatus according to claim 13, wherein the linearmovement structure comprises: a belt; and a motor configured to drivethe belt to cause the cooling turret and the plastic injection moldingmachine portion to move relatively toward and away from each other. 18.Apparatus according to claim 13, the rotary movement structurecomprises: a gearbox; and a servo motor configured to drive the gearboxto cause relative rotational movement between the cooling turret and theplastic injection molding machine portion.
 19. Apparatus according toclaim 13, wherein the axial movement structure comprises: a plurality oflinear bearings; and a cylinder configured to cause relative axialmovement between the cooling turret and the plastic injection moldingmachine portion along the linear bearings.
 20. The apparatus accordingto claim 13, further comprising: a cooling station having a plurality ofcooling structures arranged in rows configured to dispense a coolingfluid; and a cooling turret having first and second interleaved rows ofcooling tubes disposed on each of two cooling turret faces, and whereinsaid rotational movement structure moves the cooling turret to presentthe first and second interleaved rows of cooling tubes disposed on eachof the two cooling turret faces to the rows of cooling structures on thecooling station.
 21. The apparatus according to claim 20, wherein thecooling station is further configured to dispense the cooling fluid tothe first and second interleaved rows of cooling tubes on the coolingturret, such that each cooling tube on each cooling turret face receivesa first and a second flow of cooling fluid during a rotation of about630° of the cooling turret.
 22. The apparatus according to claim 20,wherein the cooling station is further configured to provide a firstflow of the cooling fluid after a first rotation of about 90°, and thento provide a second flow of the cooling fluid after a rotation of about360°, during which the axial movements between the cooling turret andthe plastic injection molding machine portion occurs.
 23. The apparatusaccording to claim 20, wherein the cooling station is further configuredto project a pressurized flow of the cooling fluid through the coolingprobes into the first and second interleaved rows of cooling tubes. 24.The apparatus according to claim 20, wherein the cooling station isfurther configured to project the cooling fluid through the coolingprobes into a distal tip of an interior of the first and secondinterleaved of cooling tubes.
 25. The apparatus according to claim 20,wherein the cooling station is further configured to provide the coolingfluid to the first and second interleaved rows of cooling tubes suchthat the cooling tubes are cooled to a temperature of less than about70° C.
 26. The cooling apparatus for a plastic injection molding machineaccording to claim 16, wherein the first movement structure comprises: abelt; and a motor configured to drive the belt to cause the coolingturret and the plastic injection molding machine portion to moverelatively toward and away from each other.
 27. The cooling apparatusfor a plastic injection molding machine according to claim 16, whereinthe third movement structure comprises: a gearbox; and a servo motorconfigured to drive the gearbox to cause relative rotational movementbetween the cooling turret and the plastic injection molding machineportion.
 28. The cooling apparatus for a plastic injection moldingmachine according to claim 16, wherein the fourth movement structurecomprises: a plurality of linear bearings; and a cylinder configured tocause relative axial movement between the cooling turret and the plasticinjection molding machine portion along the linear bearings.
 29. Thecooling apparatus for a plastic injection molding machine according toclaim 16, wherein the second movement structure comprises: a cylinderconfigured to cause relative vertical displacement between the coolingstation and the cooling turret, by causing the cooling station to moveup and down.
 30. The cooling apparatus for a plastic injection moldingmachine according to claim 16 wherein the third movement structure isfurther configured to cause the third movement structure to rotate thecooling turret to present the first and second rows of cooling tubes tothe plurality of cooling structures.
 31. The cooling apparatus for aplastic injection molding machine according to claim 16, wherein thecooling station is further configured to dispense the cooling fluid tothe first and second interleaved rows of cooling tubes on the coolingturret, such that each cooling tube on each cooling turret face receivesa first and a second flow of cooling fluid during a rotation of about630° of the cooling turret.
 32. The cooling apparatus for a plasticinjection molding machine according to claim 25, wherein the coolingstation and cooling turret are further configured to provide the firstflow of the cooling fluid after a first rotation of about 90°, and thento provide a second flow of cooling fluid after a rotation of about360°, during which the axial movements between the cooling turret andthe plastic injection molding machine portion occurs.
 33. The coolingapparatus for a plastic injection molding machine according to claim 16,wherein the cooling station is further configured to project apressurized flow of the cooling fluid through the cooling probes intothe at least first and second rows of cooling tubes.
 34. The coolingapparatus for a plastic injection molding machine according to claim 16,wherein the cooling station is further configured to project the coolingfluid through the cooling probes into a distal tip of an interior of theat least first and second rows of cooling tubes.
 35. The apparatusaccording to claim 16, wherein the cooling station is further configuredto provide a cooling fluid to the at least first and second rows ofcooling tubes such that the cooling tubes are cooled to a temperature ofless than about 70° C.
 36. The apparatus for moving a cooling turretwith respect to a plastic injection molding machine portion according toclaim 13, wherein the cooling turret further comprises: an ejectionapparatus; and a photo eye sensor, configured to ensure ejection hasoccurred.
 37. The apparatus for moving a cooling turret with respect toa plastic injection molding machine portion according to claim 16,wherein the cooling turret further comprises: an ejection apparatus; anda photo eye sensor, configured to ensure ejection has occurred.
 38. Theapparatus for moving a cooling turret with respect to a plasticinjection molding machine portion according to claim 13, wherein thecooling turret further comprises: a blower, configured to provide a flowof cooling fluid to the plastic injection molding machine portion. 39.The apparatus for moving a cooling turret with respect to a plasticinjection molding machine portion according to claim 16, wherein thecooling turret further comprises: a blower, configured to provide a flowof cooling fluid to the plurality of mold cores.
 40. A cooling apparatusfor a plastic injection molding machine comprising: a plurality of moldcores configured to form one or more bottle preforms; a rotatablecooling turret having three faces, each face having at least first andsecond rows of cooling tubes; a cooling station having a plurality ofcooling probes configured to project a cooling fluid to an interior ofmolded articles inside both the first and second rows of cooling tubesof one of the faces of said cooling turret; first movement structureconfigured to cause the rotatable cooling turret to move toward and awayfrom the plurality of mold cores; second movement structure configuredto cause said cooling station to move toward and away from said coolingturret; third movement structure configured to cause said cooling turretto rotate to alternately present the first, second, and third coolingturret faces to said cooling station; and fourth movement structureconfigured to cause said cooling turret to move parallel with respect toits axis of rotation to alternately present the first row of coolingtubes and then the second rows of cooling tubes of a cooling turret faceto the row of mold cores.
 41. The cooling apparatus according to claim32, further comprising: a post mold cooling device coupled to therotatable cooling turret, the cooling station, the mold cores, and thefirst, second, third and fourth movement structures.